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Thread: Recap TASCAM PS-520 power supply

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    Recap TASCAM PS-520 power supply

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    Hey folks,

    This is a question for everybody, but it's targeted specifically at Cory ("sweetbeats").

    I'm testing my new setup and working out the kinks. To hunt hums, I'm turning the main stereo output all the way up. When I do so, I hear electrical hiss. It's not really bad, considering that I never turn the Stereo A output up beyond 3 when using it for monitoring, but I'm concerned about the background noise when I use the stereo outs for mixdown.

    My question is: Will recapping my PSU reduce this noise? Specifically, what would the advantage be if I recap the PSU?

    And, specifically for Cory: I remember you mentioning that there were a couple of "gotchas" when you recapped your PS-520. What were they, specifically? Did it have to do with the capacitor values being different from what was on the schematic?

    Thanks in advance!
    Jeff

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    Bad caps usually result (I've read/heard) in "crackly" noise, not hiss...resistors typically contribute to "hiss"-like noise, BUT I noticed a pleasing and significant change in the noise floor in my M-520 after recapping the PSU.

    The "gotcha" in my M-520 PSU, the PS-520 I got for the M-__ AND in Ethan's M-520 PSU was that one of the caps that is labeled as a 1uF/50V cap on the parts list and on the schematic was a 10uF/35V in the unit. We chose to put what was in the manual into the untis when recapping and as far as I know all three are doing just fine. I'm pouring over my notes tonight and I can't find which cap it is but I believe it is either C4 or C5. You'll know it when you find it though if yours follows that pattern as it will differ from what is listed in the manual.

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    i'm with cory for the most part here... i wouldnt expect too much change in the hiss dept... perhaps some... but a recapped supply is a good thing no matter where you end up... as to the hiss perhaps some deoupling caps on the channels would be the way to go... typicly thats .1-.01 polypropylenes between the supplyrails at the chips... though sometimes right at the power connects of the channel can work...
    37.8% of all statistics are made up on the spot...

    hey give a guy some room... people are trying to evolve here... for crying out loud...

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    From what I have read, it seems like recapping the PSU is a good thing to do. The PSU is 20+ years old and I've read that it's generally a good idea to replace old electrolytic caps, "Just In Case".

    I've got a spreadsheet with all of the electrolytic caps, their values and the cost at Mouser.com. Just about $14 without tax or shipping added. Not bad.

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    Cory's got it... It was C005. The manual says C005 should be 1uF/50V, but if your M520 is the same as Cory's, Ethan's and mine, then you'll probably find a 10uF/35V in that spot. I'd stick with a 10uF/35V for that spot and assume that the discrepancy in the manual is from either a typo, or the Tascam engineers made a change/improvement when the M520 went into production.

    I made some notes when i re-capped my PS520 and posted them in Cory's M520 story thead. Here's a quick link to the post in case it helps a bit...

    https://homerecording.com/bbs/showpo...&postcount=416

    The sound improvement by recapping the PS was really subtle for me, but mine may have been in ok shape to begin with. If your caps are getting old, you may notice more of a difference. Besides, as dementedchord was saying, it's good to have a healthy power supply and it's a good first step to keeping the rest of the mixer healthy too.

    -Tom.

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    Thanks Tom! I couldn't find it in my own thread!

    Absolutely to all the above. I used Nichicon PW series caps (except for the 10,000uF/25V cap...I think that was a VZ series...). Anyway, good reputation, affordable and all hi-temp. I've used a bunch of them and not had one failure and all have been under 10% off spec even though all the caps I've purchased were 20% rated.

    The thing to remember here is that bad caps in a PSU can lead to ripple issues and that can be hard on everything downstream and that's where I kind get the impetus for recapping at least the powr supplies in gear I own...and it all depends on the gear of course. The design and materials used in my old Ampex PSU's still shows very clean power on the scope even at 40 years. Doesn't mean its not a good idea to recap them, but they are a different family of products entirely and I did indeed notice a very discernable difference in my M-520 after only recapping the PSU. Granted my M-520 had sat unused for over 10 years in a closet in a humid part of the world (Northwestern Washington state). My understanding is that caps can dry out when unpowered for extended (i.e. years and years) periods of time. It may have been nearly past time for mine to be done. A power supply like the PS-520 is a good starter project too. There is room in there, the PCB is pretty easy to get out and set on top of the unit even with all the hard-wired stuff connected and there aren't a lot of caps...like 13. And the PCB isn't cramped.

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